Buldresenteret åpner i dag.

Because Norwegian normally writes compound nouns as one word.

So:

• buldre = bouldering / to boulder
• senter = centre / center
• buldresenter = bouldering centre

Then the sentence uses the definite form:

• et buldresenter = a bouldering centre
• buldresenteret = the bouldering centre

This is very common in Norwegian. Where English often uses two words, Norwegian often joins them into one compound.

The ending -et marks the noun as definite singular for a neuter noun.

Here is the pattern:

• et senter = a centre
• senteret = the centre

Since buldresenter ends with senter, it follows the same pattern:

• et buldresenter = a bouldering centre
• buldresenteret = the bouldering centre

So the -et ending is doing the job that English usually does with the separate word the.

In Norwegian, the is often attached to the end of the noun instead of appearing as a separate word.

Compare:

• English: the centre
• Norwegian: senteret

So in this sentence, buldresenteret already means the bouldering centre. You do not need an extra word for the.

This is one of the big differences between English and Norwegian noun structure.

Åpner is the present tense of the verb å åpne (to open).

Basic forms:

• å åpne = to open
• åpner = opens / is opening
• åpnet = opened
• har åpnet = has opened

So Buldresenteret åpner i dag literally uses the present tense: The bouldering centre opens today.

Grammatically, it is present tense, but in context it often refers to a planned or scheduled future event.

So åpner i dag can naturally mean:

• opens today
• is opening today
• sometimes even will open today

This is very normal in Norwegian, just as English can say The store opens tomorrow.

I dag is the normal Norwegian expression for today.

Literally:

• i = in
• dag = day

So it originally means something like in the day, but you should learn i dag as a fixed expression meaning today.

Other useful time expressions are:

• i morgen = tomorrow
• i går = yesterday

Yes. That is also correct.

Both are natural, but the emphasis is slightly different:

• Buldresenteret åpner i dag. = neutral statement; focus starts on the subject
• I dag åpner buldresenteret. = puts more focus on today

This is also a good example of Norwegian word order. When a time expression like I dag comes first, the verb usually comes before the subject:

• I dag åpner buldresenteret.

That is the normal V2 word order pattern in Norwegian.

Because åpner and åpnes are different in meaning.

• åpner = opens / is opening
  This is the normal active form.
• åpnes = is opened / opens in a passive sense

In everyday Norwegian, Buldresenteret åpner i dag is the most natural way to say that the centre starts operating today.

Buldresenteret åpnes i dag is possible, but it sounds more like a passive event, as if attention is on the opening itself rather than the centre beginning business.

The letter å is a separate Norwegian vowel. It is usually pronounced somewhat like:

• the o in British English more, or
• the aw sound in law

So åpner begins with that rounded å sound.

A rough English-friendly pronunciation of åpner might be:

• OHP-ner

But that is only approximate. The important point is that å is not pronounced like the English letter name A.

It is a neuter noun:

• et buldresenter

You can tell because the head of the compound is senter, and senter is neuter:

• et senter
• senteret

In Norwegian compounds, the last part usually determines the grammatical gender and inflection. So because senter is neuter, buldresenter is also neuter.

Yes, absolutely. It is a fully natural, standard Norwegian sentence.

It has:

• a subject: Buldresenteret
• a verb: åpner
• a time expression: i dag

So it is a simple and very typical Norwegian sentence structure:

Subject + verb + time expression.